An increasing number of lamps employ a light source capsule mounted within an outer envelope. While the light source capsule can be an arc discharge tube, a tungsten halogen capsule or other light source, particular reference herein will be made to lamps employing a tungsten halogen light sources. Such light sources are known and operate on the regenerative action of the halogen cycle.
One form of lamp that can utilize such a light source is a parabolic reflector (PAR) (“parabolic aluminized reflector”) lamp. Such lamps typically comprise, for example, a tungsten halogen capsule comprised of quartz or a hard glass, mounted in a pressed borosilicate glass body having a reflective coating applied to the inner surface of the body. A pressed glass lens usually covers the front aperture of the body and may contain optical elements to give a desired beam shape, for example, a spot or flood configuration. General service PAR lamps typically have a medium screw base attached to the body for electrical connection to 100V to 240V circuits. In many tungsten halogen PAR lamps the hard glass capsule contains stiff electrical lead-ins that connect to the relatively deformable inner leads of the light source and that are themselves pressed into the seal area of the capsule. Such capsules are shown in U.S. Pat. No. 5,660,462 (Bockley, et al.), and U.S. Published Patent Applications 2005/0212396 (Oetken, et al.) and 2006/0043890 (Kling) (all of which are assigned to the assignee of the instant invention). Often, in such lamps the capsule is supported by crimping the leads into metal eyelets that are formed in the base of the envelope body.
Most PAR lamps on the market are assembled by inserting the capsule from the front aperture and attaching the capsule lead-ins to the heel of the reflector body by eyelets, ferrules, ceramic body or cement. In some cases additional support is provided by a metal disc surrounding the capsule press. Many PAR38 halogen lamps (a particularly popular size) typically have a hard glass or quartz capsule supported solely be crimping both capsule lead-ins into metal eyelets compressed into two holes in the reflector heel. This requires a very tight tolerance on reflector hole dimensions that increases the cost of the reflector. In another common PAR lamp construction, the capsule is inserted into a metal disk that rests on a shelf in the reflector neck. Axial movement is prevented by crimping metal eyelets onto capsule lead-ins near the outer reflector heel surface. This construction does not require tight reflector hole tolerances, but the added metal disk and additional assembly operations increase the manufacturing costs. Such a technique is shown in U.S. Pat. No. 5,751,095 (Zalar), which also employs multiple glass or ceramic insulators to guide the lead-ins to the screw base.
Further, in prior art PAR lamps some of the light entering the neck opening is lost due to multiple reflection and absorbtion by the mount and capsule components and does not contribute to the beam. It is well known that neck opening cross-sectional area should be as small as possible to maximize bean intensity and lamp efficiency (as defined by lamp lumens divided by source lumens). Both inner and outer surfaces of the reflector must have a suitable draft angle for removal from a mold. Pressed glass used for PAR lamps typically require a minimum draft angle of 3 degrees and in practice, a 5 degree draft angle is typically employed. When the capsule is supported solely by lead-ins crimped into eyelets, the neck ID must be large enough to allow room for the eyelet flares.
Additionally, various forms of brackets have been employed to support and mount light sources contained within capsules, such as are shown in U.S. Pat. No. 6,741,034 (Scholz) (an arc tube within a shroud); U.S. Pat. No. 7,008,096 (Coushaine, et al.) (a tungsten halogen capsule); U.S. Pat. No. 7,261,451 (Coushaine, et al.) (tungsten halogen or arc discharge tube); U.S. Pat. No. 7,207,695 (Coushaine, et al.) (light emitting diodes); and U.S. Published Patent Applications 2007/0069652 (Smith et al) (arc discharge tube or tungsten halogen capsule); 2008/0054775 (Kling, et al.) (tungsten halogen capsule); 2008/0057819 (Kling) et al (tungsten halogen capsule); 2008/0272695 (Misiaszek) (tungsten halogen capsule) and 2009/0103294 (Zhang et al.) (light emitting diodes). With the exception of the latter publication, the remaining patents, pending patent applications and publications listed directly above in this paragraph are assigned to the assignee of the instant invention.
While all of the above-recited solutions have provided workable lamps, they all present problems that, if eliminated or reduced, would clearly supply more economical and/or more efficient lamps.